Automatic clamp apparatus having lateral motion resistance for IV infusion sets

ABSTRACT

A clamp apparatus for selectively occluding a resilient tube to prevent free flow of fluid in the tube. The device comprises a base member to which the resilient IV tube is attached or through which it passes, and a slide clamp that slides relative to the base member and relative to the tube. The aperture in the slide clamp has a relatively open hole at one end, through which the tube passes when the slide clamp is an open position, allowing fluid to flow through the tube. The aperture also has a relatively constricted slot at the other end, through which the tube passes when the slide clamp is in the occluding position, preventing fluid flow through the tube. The slide clamp includes a groove for receiving a cooperatively shaped rib on the base member. The groove and rib are configured to guide relative movement between the slide clamp and the base so as to prevent significant lateral movement.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. application Ser. No.10/892,941, filed Jul. 16, 2004, which is presently pending, theentirety of which is hereby incorporated by reference.

FIELD OF INVENTION

The invention is generally related to clamps used on flexible IV tubingin the field of intravenous (IV) infusion devices such as peristalticpumps, and more particularly, to clamping devices used to prevent thefree flow of fluids through an IV tube when the infusion pump isdisengaged from the IV tube. Further, the invention is related to moreconsistently performing clamps to lessen the possibility of false clampalarms in medical instruments having clamp detectors.

BACKGROUND OF THE INVENTION

It is a common practice to deliver fluids such as medications to apatient intravenously by means of a pumping device, such as aperistaltic pump. Such pumps are useful because they can deliver themedication in a highly controlled and precise fashion, and because theydo so without coming in contact with the medication. The fluid is movedthrough a flexible IV tube by pressing a pumping member against the tubesufficiently to move the fluid in the tube downstream towards thepatient. In the case of peristaltic mechanisms having multiple pumpingfingers, the fingers are moved against the tube in a sequential mannerfrom upstream to downstream to sequentially occlude the tube therebymoving the fluid in the tube downstream towards the patient. When the IVtube is mounted correctly in the pump, the IV tube is at all timesoccluded by one of the pumping members, thereby preventing the “freeflow” of fluid to the patient. “Free flow” of medical fluids isundesirable since the flow of the fluid is uncontrolled and theprescribed treatment is not followed.

It is common for the peristaltic pumping mechanism to be located in ahousing with a hinged door. The tube through which the fluid is to bemoved is placed in contact with the pumping mechanism inside the door,with the ends of the tubing typically extending out the top and bottomof the door opening. As the door is shut over the tube, a platen on theinside of the door presses against the IV tube to provide a backingsurface against which the pumping members can occlude the tube. Theplaten is typically spring loaded, although not always, against thepumping mechanism so that one or more of the pumping fingers of thepumping mechanism occludes the tube once the door is shut over the tube.This then prevents free flow while the door is shut.

This arrangement of the W tube relative to the pumping mechanismrequires that there be some means for preventing flow in the tube whenthe door of the pump is open. Merely opening the pump door would relievethe tube from the occluding pumping mechanism/platen combination andfree flow could possibly occur. This could result in the uncontrolledinfusion of medication into the patient under the influence of thestatic head pressure in the tube, or blood from the patient could flowback into the IV tube. Known devices for preventing the unwanted flow inthe tube include manual clamps on the tube separate from the infusionpump, and automatic occluding devices mounted on the pump. The manualdevices require some manipulation skill on the part of the attendingtechnician, and there is always the chance that the technician willforget to properly time the manual clamping process of the tube beforethe door of the pump is opened. Furthermore, the door may beaccidentally opened, resulting in free flow in the tube.

Automatic devices mounted on the infusion pump for assisting in clampingand unclamping infusion tubes have improved. In particular, thereliability in timing the occlusion and release (unocclusion) of thetube with the disengagement and engagement, respectively, of tube withthe pumping members has improved. Typically, the action of opening thedoor is relied upon to initiate the occlusion of the IV tube by a clamp,and the action of closing the door is relied upon to initiate therelease or unocclusion of the tube by an IV tube clamp. However, therestill can occur the possibility of an inadvertent free flow of fluidthrough the IV tube due to operator error in regard to use of suchdevices.

Additionally, medical instruments having such automatic devicestypically have clamp detectors to sense the correct operation of theclamp. The detector or detectors may be used to determine if the clampis in the unoccluded position or occluded position. The processor of themedical instrument monitors the detector or detectors and may beprogrammed to advise the operator accordingly. For example, theprocessor may monitor the flow clamp detector to determine if thedetector indicates that the clamp is in the unoccluded position. Theprocessor may also monitor other detectors of the instrument, such as adoor open detector of an infusion pump. As the processor receivesvarious detector signals, or pump configuration signals, and if itdetermines from those detectors or from other information that indicatesthe configuration of the pump that the flow clamp should be in theoccluded position for this configuration, the processor may provide analarm if the clamp detector indicates that the clamp is in theunoccluded position. If such alarms are based on clamp detectorinformation that is not accurate, they can become a nuisance to thenursing staff. Therefore, accurate clamp position or configurationdetection systems are desired.

Hence, those skilled in the art have identified a continuing need toprovide an improved apparatus that will automatically and positivelyocclude an IV tube before the occluding pumping mechanism is disengagedfrom the tube. A further need has been recognized for an apparatus thatwill automatically and positively maintain the IV tube in an occludedstate until after the occluding pumping mechanism is engaged with thetube. A still further need has been recognized for an apparatus thatwill reliably occlude the IV tube, that is inexpensive to manufacture,and is easy to use. Yet a further need has been recognized for anapparatus that can be manually operated between occluding andnonoccluding configurations. In addition, a need has been recognized foran apparatus for which occlusion of a flow clamp is reliably detected bya sensor associated with pumping device. The present invention fulfillsthese needs and others.

SUMMARY OF THE INVENTION

Briefly and in general terms, the present invention is directed to aclamp apparatus for selectively preventing fluid flow through aresilient tube and comprises a base having a tube aperture at which theresilient tube may be located, the base having a longitudinal centerline, a slide clamp slidably mountable on the base for linear movementbetween an occluding position and an open position, the slide clamphaving a longitudinal center line, a clamp aperture formed in the slideclamp for receiving the tube therethrough, a constricted region formedin the clamp aperture, the constricted region occluding the tube toprevent fluid flow through the tube when the slide clamp is in theoccluding position, an open region formed in the clamp aperture, theopen region allowing fluid flow through the tube when the slide clamp isin the open position, a locking device formed on the slide clamp and aflexible cantilevered locking arm mounted on the base, the locking armhaving a release tab formed thereon but located at a position offsetfrom the longitudinal center line of the base, the locking arm beingbiased toward a locking position wherein the locking arm engages thelocking device of the slide clamp to prevent movement of the slide clampfrom the occluding position to the open position, and the release tabbeing movable to deflect the locking arm wherein the locking arm isdisengaged from the locking device to allow subsequent linear movementof the slide clamp from the occluding position to the open position. Agroove is formed in one of the slide clamp and the base, the grooveextending substantially parallel to the longitudinal center line of thebase or slide clamp in which the groove is formed. A rib is formed inone of the slide clamp and the base and extends substantially parallelto the longitudinal center line of the slide clamp or the base in whichit is formed, the rib sized and shaped to slide within the groove torestrict lateral movement of the slide clamp and base relative to eachother.

In accordance with another aspect of the invention, the tube aperture ofthe base slidably receives the resilient tube such that the base may beslid along the tube to a selected position when the slide clamp is inthe open position.

In other aspects of the invention, the locking arm further comprises arelease tab for releasing the flexible arm from the slide clamp, toallow subsequent movement of the slide clamp from the occluding positionto the open position. Further, the base comprises a stop surface locatedat a position adjacent the release tab to interfere with movement of therelease tab beyond a preselected range of movement. The locking devicecomprises a detent in the slide clamp into which the locking arm isbiased and located when the slide clamp is in the occluding position,the detent being large enough to receive the locking arm without contactwhile the slide clamp is in the occluding position whereby the lockingarm is under no stress. The slide clamp further comprises a ramp toreceive the locking arm when the slide clamp is in the open position,the ramp formed to be deeper than the arm whereby the arm is not understress when the slide clamp is in the flow position. The ramp is formedto guide the locking arm into a detent formed in the slide clamp as theslide clamp is being moved from the open position to the occludingposition to thereby lock the slide clamp in the occluding position.

In yet other aspects, the aperture of the slide clamp is approximatelytear-drop shaped, the constricted region comprises an elongated slotportion, the flow region comprises a rounded portion, the tube islocated in the slot portion when the slide clamp is in the occludingposition, and the tube is located in the round portion when the slideclamp is in the open position.

In additional detailed features, the tube aperture comprises a tubesleeve within which a resilient tube end may be permanently mounted. Thetube aperture comprises a fluid passageway through the base, whereby theresilient tube is connected in fluid communication with the passageway.Further, the clamp apparatus comprises a pressure interface devicelocated in line with the resilient tube, the pressure interface devicehaving a pressure membrane mounted in a housing, the pressure membraneformed to conduct pressure increases and decreases of the resilienttubing to a pressure sensor located in a medical instrument.

In further aspects in accordance with the invention, the slide clampfurther comprises a front pushing flange large enough to receive a digitof an operator used to push the clamp apparatus into position in amedical infusion pump, the pushing surface being concave. The releasetab of the locking arm is located at a position other than behind thepushing flange. In another detailed aspect, the release tab is locatedat a sideways position in relation to the longitudinal centerline of theslide clamp. Additionally, the base comprises a rounded mounting endwhereby pressing the clamp into operative position in an infusion pumpis facilitated.

The novel features of this invention, as well as the invention itself,both as to its structure and its operation, will be best understood fromthe accompanying drawings, taken in conjunction with the accompanyingdescription.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of the automatic clamp apparatus inaccordance with aspects of the present invention showing the slide clampin the occlusion position at which it is partially withdrawn from thebase;

FIG. 2 is a front left-side perspective view of the slide clamp shown inFIG. 1 showing the aperture, the detent, the ramp, and the pushingflange;

FIG. 3 is a bottom right-side perspective view of the slide clamp shownin FIG. 1 showing the aperture, the pushing flange, and the pullingprojections;

FIG. 4 is a top plan view of the slide clamp of FIGS. 1 through 3;

FIG. 5 is a left side, partially cutaway view of the slide clamp ofFIGS. 1 through 4 showing a pulling projection, the detent, and theramp;

FIG. 6 is a top, left side perspective view of the base showing alocking arm, a release tab, a tube aperture, and a lateral motionrestriction rail and rib;

FIG. 7 is a bottom, right side perspective view of the base showing thelocking arm, release tab, and the lateral motion restriction rail andrib;

FIG. 8 is a right side plan view of the base showing the release tab;

FIG. 9 is a cross-section left side view of the base showing the lockingarm and release tab;

FIG. 10 is a left side view of the base showing the tube aperture, therelease tab, and a portion of the locking arm, also shown in the angleof the locking arm with the upper base surface;

FIG. 11 is a bottom view of the base;

FIG. 12 is a top, left side perspective view of the automatic clampapparatus of FIG. 1 in which the slide clamp has been inserted fullyinto the base resulting in the flow configuration;

FIG. 13 is an operational view in which the tube is occluded by theaperture of the slide clamp, but a release boss and a pushing boss areabout to move the slide clamp to the open or flow position;

FIG. 14 is an operational view in which the tube is unoccluded for flowand a pulling hook is about to pull the slide clamp to the occludingposition; and

FIG. 15 is a view of the clamp apparatus having a pressure interfacedevice located as part of the tube upstream from the clamp forcommunicating the line pressure to a pressure sensor;

FIG. 16 shows the use of an operator's finger against the pushingsurface of the slide in aligning the clamp apparatus of FIG. 1 with theflow clamp mounting slot in an infusion pump, the clamp apparatus beingin the configuration where the slide is pulled partially out of the baseand locked in that position to occlude a medical fluid flow tube;

FIG. 17 shows the continued use of an operator's finger against thepushing surface of the slide clamp in pushing the clamp apparatus ofFIG. 1 into the flow clamp mounting slot in an infusion pump, the clampapparatus being in the occluding configuration;

FIG. 18 is a top, more schematic view of the slide clamp mounted withinthe base showing the operator's finger against the pushing surface ofthe slide clamp with the slide clamp locked in the occluding position,the figure also showing the use of a detector system to determine thatthe slide clamp is not in the unoccluded position;

FIG. 19 is also a top schematic view of the clamp apparatus of FIG. 18showing that the slide clamp has been linearly slid into the base intothe unoccluded position so that medical fluid may flow through the slideclamp apparatus, the figure also showing that the slide clamp nose hasmoved far enough into the base to interrupt the beam of the detectorthereby indicating to the detector that the slide clamp is in theunoccluded position;

FIG. 20 is also a top schematic view of the clamp apparatus of FIG. 18but in this case showing that the slide clamp has experienced lateral orrotational motion due to the operator pushing against the pushingsurface of the slide clamp at an angle of greater than zero degrees tothe base thereby interrupting the detector beam, even though the slideclamp remains in the occluded position;

FIG. 21 is a perspective view of the automatic clamp apparatus inaccordance with aspects of the present invention showing the slide clampin the occlusion position and showing a longitudinal rib on the basedisposed within a longitudinal groove formed in slide clamp; and

FIG. 22 is a perspective cut-away view of the automatic clamp of FIG. 16showing a flared opening formed by the groove on the slide clamp forguiding the rib within the groove, and showing side walls of the ribsliding against slide walls of the groove so as to prevent relativelateral movement between the slide clamp and the base.

DESCRIPTION OF PREFERRED EMBODIMENTS

Referring now to the drawings with more particularity, in which likereference numerals refer to like or corresponding elements among theseveral views, FIG. 1 presents an automatic clamp apparatus 20 forintravenous (herein referred to as “IV”) infusion sets used in pumpdevices. The clamp apparatus 20 comprises generally a relatively open,box shaped base or frame 22 and a mating slide clamp 24. Both parts canbe formed by injection molding from various plastic materials. The solidbody of the slide clamp 24 is shaped and sized to slide within the base22. In the embodiment shown, the base 22 has a tower 26 formed on thetop surface 28 of the base, with the tower extending upwardly from thebase and substantially perpendicular to the base. The top end 30 of thetower 26 is formed as a female tube connector into which a resilient IVtube can be attached. A pumping tube or other type of fluid conduit canbe attached to the base by other means if desired. The open bottom end32 of the tower is attached to the base and it is also formed as afemale tube connector into which an IV tube or other conduit can beattached. The IV tube and the pumping tube can be the same tube ifdesired, simply threading the IV tube through the tower, through thebase, and through the slide clamp such that the automatic clampapparatus 20 can be slid along the IV tube to a desired location.

Referring now also to FIG. 2, the slide clamp 24 is penetrated from itstop surface 34 to its bottom surface 36 by an elongated aperture 38. Theelongated dimension of the aperture 38 is arranged on the slide clamp tobe parallel to the direction of the relative sliding movement betweenthe base 22 and the slide clamp 24. The aperture 38 of the slide clampcomprises an open portion 40 and an occluding portion 42. The openportion is large enough so that a tube received by the open portionwould not be occluded whereas the occluding portion is small enough sothat it would occlude a received tube. The width of the slot of theoccluding portion is sufficiently small that a selected IV tube passingthrough the slot would be completely occluded and would remain occludedagainst a foreseeable range of fluid pressures in the IV tube. The rangeof pressure against which the tube would remain occluded would includeat least the static head anticipated during normal use of the infusionapparatus.

The slide clamp 24 also includes a pushing flange 44 at its front edge46. The pushing flange is somewhat concave, although the “concave”surface may not necessarily be curved; it may in fact have convergingstraight surfaces or surfaces of other shapes. The purpose of thepushing flange is to guide the digit of an operator to the approximatecenter of the slide clamp for the purpose of mounting the entireautomatic clamp apparatus 20 (FIG. 1) into an infusion pump. Such anoperation may be seen by reference to U.S. Pat. No. 6,629,955 to Morris,particularly FIG. 10. U.S. Pat. No. 6,629,955 to Morris is incorporatedherein by reference. Guiding the digit of an operator to the center ofthe pushing flange is more likely to result in the application ofcenterline force on the automatic clamp apparatus and thereby to resultin the correct mounting of the clamp apparatus in the pump. Forconvenience, the shape of the pushing surface of the pushing flange 44is referred to as “concave” although the surfaces may be other thancurved, as discussed above. It will be noted that in this embodiment,the aperture 38 is also located on the longitudinal centerline 47 of theslide clamp.

Also shown in FIG. 2 is a locking detent 48 having a locking detent edge50. The particular operation of the detent will be shown later but itspurpose is to prevent movement of the slide clamp from the occludingposition to the open position in the base without intended action.Further shown is a ramp 52 at the front of the slide clamp for receivinga locking arm of the base when the slide clamp is in the open position.

Referring now to the perspective view of FIG. 3 and the views of FIGS. 4and 5, the bottom surface 36 of the slide clamp 24 includes pullingprojections 54 that project downwardly from the bottom surfacepresenting a substantially vertical pulling face 56 to engage the latchon the door of the pump housing (not shown) to withdraw the slide clamp24 partially out of engagement with the base 22 before the door isopened. Pulling or withdrawing the slide clamp partially out of the basemoves the slide clamp from its open position to its occluding position(FIG. 1). The pushing flange 44 of the slide clamp also presents asubstantially vertical pushing face against which the door of the pumpor some other device pushes to fully insert the slide clamp into thebase when the door of the pump is closing or after it has been closed.Pushing the slide clamp into full insertion with the base moves theslide clamp from its occluding position to its open position. Also shownin FIGS. 4 and 5 are the detent 48 and the ramp 52. Both are formed inthe material of the slide clamp and the depth of both can be best seenfrom FIG. 5.

Turning now to the base, there is shown in FIG. 6 the base 22 with aflexible cantilevered locking arm 60 that is molded into the top surface28 of the base, with its distal free end 62 biased downwardly below thetop surface 28 of the base. Biasing of the free end downwardly isaccomplished by molding the locking arm in a downwardly slopedconfiguration, but the biasing could also be accomplished by the use ofsprings or other means. A release tab 64 is formed on the locking arm60, projecting upwardly from the locking arm in the general direction ofthe tower 26. It will be noted that the release tab 64 is located at aposition sideways to the tower 26. The release tab is also offset fromthe longitudinal centerline 66 of the base. The free end 62 of thelocking arm 60 can be flexed upwardly by pressing the release tab 64 ina direction parallel to the centerline 66. Without departing from thespirit of the invention, multiple locking arms and tabs offset from thecenterline of the base may be used in place of the ones shown.

It should also be noted that the depth of the detent 48 (FIG. 5) and thesize and angle of the locking arm 60 are carefully selected so that whenthe locking arm is located in the detent, it is unstressed. That is, itdoes not touch the bottom of the detent with any significant force. Thisis important in that if the locking arm is formed of plastic material orother material that exhibits “creep,” it may change shape if it isexposed to constant stress for an extended period. For example, if theclamp apparatus were stored in the occluding position (FIG. 1) for anextended period where the locking arm was in contact with the bottom ofa shallower detent and was under continual stress due to constantcontact with the detent, the locking arm may creep to where that storageposition is the new at rest position of the locking arm. The locking armwould then become less effective. Thus, forming the detent and lockingarm as described above so that the arm is unstressed will result in aclamp apparatus that is unaffected by storage. Similarly, the ramp isalso of a depth that leaves the locking arm unstressed when at thelowest point of the ramp, as is the case in the open position shown inFIG. 12.

The base also includes its side edges 68 formed into rails 70 that lieparallel to the direction of the relative sliding movement of the slideclamp in the base (FIG. 1). When the slide clamp 24 is slidingly engagedwith the base 22, the slide clamp fits in a sliding fashion through thetwo rail channels 72 in the base. Alignment of the slide clamp with thebase is accomplished by the fit of the slide clamp into the railchannels. Turning now to FIG. 7, the rails 70 and channels 72 can beseen more clearly. Additionally, it will be noted that the entireproximal end 74 of the base is enclosed. The center section 76 has beenleft open to accommodate the pulling projections of the slide clamp, aspreviously shown. Also more clearly seen is the distal free end 62 ofthe locking arm, as well as the releasing tab 64.

FIG. 8 shows a stop 78 formed on the top surface 28 of the base 22 thatlimits the range of movement of the release tab 64. In particular, astop surface 80 is spaced away from the back of the releasing tab by apreselected distance so that the tab cannot be overstressed by bendingit too far. Referring also to FIG. 9, a cross-section of the locking arm60 with releasing tab 64 formed at its end is shown. It will be notedthat the locking arm is molded as part of the base and is in acantilever form. The releasing tab 64 is disposed at approximatelyninety degrees to the locking arm but because the locking arm is formedat an angle to the upper 28 and the lower 82 surfaces of the base 22 soas to engage the slide clamp, the ninety degree angle of the releasingtab with the locking arm is other than ninety degrees to the top surfaceof the base. FIG. 9 more clearly illustrates the downward slope of thelocking arm 60 to create the necessary downward bias to engage thedetent 48 and locking edge 50 of the slide clamp to prevent the slideclamp from being moved to its open position until the locking arm 60 ismoved out of the detent by intended action of the operator.

Referring now to FIG. 10, a right side view of the base is provided. Itwill be seen that the angle of the top surface of the locking arm isapproximately 172.86 degrees relative to the top surface 28 of the base.This is also seen in FIG. 9. It has been found that thickening thelocking arm and providing the angles shown results in repeatableperformance. That is, when a releasing boss 90 (shown in FIG. 13)presses against the releasing tab 64, the tab and locking arm will riseaway from the base and therefore away from the mounted slide clamp thusreleasing the slide clamp for movement to the open position. This isdiscussed below in more detail. FIG. 11 presents a bottom view of thebase 22 showing more clearly the distal end 62 of the locking arm thatis received by the detent 48 of the slide clamp 24. Further, FIG. 11shows the aperture 49 through the base for the tube.

FIG. 12 shows the assembled slide clamp 24 and base 22 into anoperational automatic clamp apparatus 20 in accordance with aspects ofthe invention. Further, the clamp apparatus 20 is in the open positionduring which fluid may flow through the clamp apparatus. It will be seenthat the distal free end 62 of the locking arm 60 resides in the ramparea 52, but the ramp is formed to be deep enough so that the distalfree end 62 of the locking arm is not touching the material of the baseand therefore, the locking arm is in an unstressed condition. In thisconfiguration, the clamp apparatus 20 is in its smallest form therebyfitting into a pump with a closed door.

FIGS. 13 and 14 show in general how the automatic clamp apparatus 20 inaccordance with aspects of the invention interacts with the door of apump housing. FIG. 13 shows the slide clamp 24 in its occluding positionrelative to the base 22, with the slide clamp partially withdrawn fromthe base and the distal free end 62 of the locking arm 60 engaging thelocking detent 48 (not shown) to hold the slide clamp in its occludingposition. FIG. 14 shows the slide clamp in its open position with theslide clamp fully inserted within the base and the distal free end 62 ofthe locking arm flexed upwardly a sufficient amount to clear the detent48.

Operative elements of the door and latch mechanism are shownschematically and designated as elements 90, 92, and 94, to illustratetheir interaction with the automatic clamp apparatus of the presentinvention. A releasing boss 90 can be formed on the door and positionedto contact the release tab 64 as the door is moved to the closedposition, and to press the release tab up and back. A pushing boss 92can be formed on the latch mechanism and positioned to contact thepushing flange 44 on the slide clamp 24 as the latch is engaged to pushthe slide clamp from its occluding position (FIG. 13) to its openposition (FIG. 14). Finally, one or more pulling hooks 94 can be formedon the latch mechanism and positioned to contact the pulling projections54 as the latch is disengaged to pull the slide clamp 24 from its openposition to its occluding position.

The releasing boss 90 and the pushing boss 92 of the door move generallyto the right direction as seen in FIG. 13 when the door of the pump ismoved to the closed position. The pulling hook 94 of the latch mechanismcan be made to move generally to the left as seen in FIG. 14 when thelatch is being disengaged, and to the right when the latch is beingengaged, it being understood that other elements (not shown) of thelatch mechanism perform the actual latching of the door in the shutposition. In addition, the pulling hook 94 can rotate in the clockwisedirection from the position shown, relative to the remainder of thelatch mechanism, against a spring bias. For convenience, the conduitthrough the automatic clamp apparatus 20 is shown as a tube 96 in FIGS.13 and 14. In FIG. 13, the tube 96 is occluded by the slide clampaperture and is spread into the occluding slot of that aperture. In FIG.14, the tube is in the flow configuration. As mentioned above, a tubemay or may not be used as the conduit through the clamp apparatus 20. Atower may be used with parts of tube formed to the tower.

Referring briefly to FIG. 15, the inclusion of a pressure interfacedevice 100 upstream of the automatic clamp apparatus 20 is shown. Thispressure interface device may take the form of a pressure diaphragmhaving a size and configuration to be mounted to a pressure sensor thatis a part of the infusion pump to which the clamp apparatus is to bemounted. Such a pressure diaphragm device is shown in U.S. Pat. No.4,398,542 to Cunningham, and incorporated herein by reference. A sensorusable with such a pressure diaphragm is shown in U.S. Pat. No.4,404,440 to Busche, also incorporated herein by reference. Mountingsuch a pressure diaphragm in line with the automatic clamp apparatus ofthe invention would restrict movement of the clamp apparatus along theline since it will need to be adjacent the pressure diaphragm to befitted into the pump. In such a case, the tower 26 may be used as amount for the pressure diaphragm device.

Operation

To use the automatic clamp apparatus 20 of the present invention, theslide clamp 24 is assured to be in the occluded position, as shown inFIG. 1. Because the locking arm 60 is located in the detent 48, theslide clamp cannot be moved from the occluding position to the openposition unless the release tab 64 is actuated. While in the detent, thelocking arm is unstressed. The upstream end of the IV tube 96 (FIGS. 13and 14) is connected to a fluid supply (not shown) of the chosen fluidto be pumped. The administration set containing the automatic clampapparatus of the invention may be primed if necessary by the operatorpressing a digit against the release tab to move it and the locking armupwards out of the detent and another digit against the pushing flange44 to move the slide clamp to the open position. As the slide clamp isinserted into the base 22, the locking arm moves down the ramp 52 to thebottom of the ramp (FIG. 12) where it is unstressed. Priming may nowoccur. Once primed, the pushing flange is grasped by the operator andwithdrawn from the base to restore the slide clamp to the occlusionposition as shown in FIG. 1 so that the free flow of fluid through theIV tube cannot occur.

The door of the pump housing is opened and the automatic clamp apparatus20 and tubing above and below the clamp apparatus 20 are installed intothe pump appropriately. The pushing flange 44 is used by the operator toreceive a digit of the operator for pushing the entire clamp apparatus20 into the appropriate cavity of the pump. The clamp apparatus shouldremain in the occlusion configuration (FIG. 1) during this installationinto the pump. Because the release tab 64 is off center in relation tothe pushing flange, the chances of the operator pressing it instead of,or with, the pushing flange are greatly reduced.

The upstream and downstream tubing is now engaged with any other devicesthat exist, such as an air-in-line sensor, pressure sensors, etc.Especially, the pumping tube 96 is placed in contact with the pumpingmechanism, and the door of the pump is then shut. FIG. 13 shows theslide clamp 24 in its occluding position, with the release boss 90 aboutto contact the release tab 64 as the door of the pump is shut. As thedoor is completely shut, the release boss 90 presses the release tab 64upward thereby flexing the locking arm 60 upward and out of the detent48 thereby permitting movement of the slide clamp so that it can beinserted into the base. After the door is completely shut, the latchingmechanism is latched, causing the pushing boss 92 to push the slideclamp 24 and insert it into the base to its open position as shown inFIG. 12. FIG. 14 shows the slide clamp 24 in its open position, with thepulling hook 94 having pivoted behind the pulling projection 54. Thepump can then be operated in the conventional fashion to purge the IVtube 96 of air, and the IV tube 96 can be connected to a venous accesssite.

When the pump door is to be opened, the boss 92 and the hook 94 will bemoved to the left, causing the pulling hooks 94 to contact the pullingprojection 54 of the slide clamp 24 and withdraw the slide clamp 24 fromthe base to its occluding position. The latching mechanism can beconstructed by known means so that only after this occlusion occurs willthe door be unlatched. At this time, the door can be opened. The lockingarm 60 having engaged the locking detent 48 maintains the slide clamp 24in its occluding position, even if the slide clamp 24 is pushed towardthe base 22 with considerable force.

The latching mechanism can also be constructed by known means so thatwhen the door has been unlatched, the latching mechanism can not bemoved back to its latched position until the door has been shut.Therefore, if the door is to be shut, the releasing boss 90 will pressthe release tab 64 upward to release the locking arm 60 from engagementwith the detent 48, and the slide clamp 24 can be subsequently moved tothe open position as explained before.

Lateral Motion Resistance

Turning now to FIG. 16, alignment of the automatic clamp apparatus 20with a mounting slot 140 in an infusion pump 142 is shown. The operator144 has placed his/her index finger 146 against the pushing surface 44of the slide clamp 24. The clamp apparatus is in the occludingconfiguration in which fluid flow through the tube 96 is blocked. Suchoccluding configuration is shown in more detail in FIGS. 1 and 13.Because of the detent 48 in the slide clamp and the locking arm 62residing in that detent, the operator's action of pushing against thepushing surface of the slide clamp should push the entire clampapparatus 20 together. It can be noticed that the off center position ofthe release tab 64 makes it less likely that the operator's finger 146will inadvertently press against that tab.

FIG. 17 shows the same configuration as FIG. 16 except that the clampapparatus 20 is now partially mounted within the mounting slot 140 ofthe pump 142. As before, the operator 144 is using his/her index finger146 to push the entire apparatus 20 into the mounting slot. Because ofthe locking action of the locking arm of the base against the slideclamp as shown in FIG. 1 and described above, the operator's forceplaced against the slide clamp pushing surface 44 by his/her finger willnot move the slide clamp relative to the base but instead moves theentire apparatus 20 into the mounting slot. Force from the operator in adirection aligned with the longitudinal axes of the slide clamp 47 andbase 66 will provide maximum effect for pushing the clamp apparatus intocorrect mounting position in the pump. Once again it can be seen thatthe off center position of the release tab 64 makes it less likely thatthe operator's finger will inadvertently press against that tab therebyinadvertently moving the slide clamp 24 into the base 22 and placing theapparatus in the unoccluded configuration.

Referring now to FIGS. 18 through 20, the operation of detectors usedwith the clamp apparatus can be seen. Referring first to FIG. 18, adetector system 148 comprises an emitter 150 and a receiver 152. Thebase 22 of the clamp apparatus has a section 154 that is transparent tothe energy used by the detector system. Thus the beam 156 emitted by theemitter will be received by the receiver if nothing blocks or interruptsthe beam. In another embodiment, the entire base may be formed of amaterial that is transparent to the detector system energy. A processor158 connected to the emitter and the receiver will conclude that theslide clamp 24 is in the occluded position if the detector system beamis uninterrupted, as shown in FIG. 18. Further, FIG. 18 is a top view,with certain details left out for the purpose of clarity, of FIGS. 16and 17. It can be seen that the operator's 144 finger 146 is applyingforce to the pushing surface 44 of the slide clamp 24 at zero degreesangle to the longitudinal axes 47 and 66 of both the slide clamp and thebase 22 respectively. Thus, no lateral or rotational force is applied tothe slide clamp relative to the base and the slide clamp will remain inits locked position relative to the base without interrupting thedetector beam.

In the base 22 of FIGS. 18 through 20, a portion through which the beamwill traverse is formed of material that is sufficiently transparent tothe energy of the beam that the receiver will receive a sufficient powerlevel of the beam when the slide clamp is not present. Likewise, theslide clamp is formed of a material that will sufficiently attenuate theenergy of the beam so that the receiver will not receive a sufficientpower level of the beam when the slide clamp is present. In someinfusion pump systems, all detectors are functioning when the pump ispowered. Also in some infusion pumps, a detector exists that detectsthat a clamp apparatus has been slid into the mounting slot 140. In thecase of FIG. 18, if a clamp apparatus detector existed, it may be usedto detect the existence of the base 22 slid into the mounting slot 140(see FIG. 17) providing the processor with further configuration data.

FIG. 19 presents the slide clamp 24 linearly slid into unoccludingposition in the base 22. The detector beam 156 is interrupted at thenose 160 of the slide clamp. Thus the receiver 152 will not receive thebeam and will report this to the processor 158. Depending on otherconditions of the pump, the processor may or may not report an alarmthat the clamp apparatus 20 is in the unoccluding configuration. Forexample, if the door of the infusion pump is closed, and the detectorbeam is interrupted as shown in FIG. 19, the processor is unlikely toreport an alarm because the tube will be occluded by the pumpingmechanism (not shown) of the pump. However, turning now to FIG. 20, itwill be seen that the detector beam 156 is interrupted as in FIG. 19,but the clamp apparatus is not in the occluding configuration. The slideclamp 24 is not fully slid into the base and the door of the pump islikely open since the operator's 144 finger 146 is pushing against theslide clamp. In such a configuration, the processor 158 will receivesignals that the pump door is open but that the slide clamp detectorbeam has been interrupted. In another pump where a base detector exists,the processor may receive data that a base has been introduced into themounting slot, the slide clamp 24 has interrupted the slide clampdetector beam, but the door is open. Accordingly, in certaininstruments, the processor may provide an alarm that the clamp apparatusis in an unoccluding configuration. The processor may then inform theoperator that the slide clamp should be moved to the occluding position.

The cause of the alarm in FIG. 20 is the lateral or rotational movementof the slide clamp 24 relative to the base 22. That is, the operator 144has placed a force on the slide clamp while pushing the entire clampapparatus 20 into the pump that has caused the slide clamp to movelaterally or rotationally in relation to the base. The lateral movementis so great that the nose 160 of the slide clamp has interrupted thedetector beam 156. It will be noted that the operator has pushed on thepushing surface 44 of the slide clamp at an angle in this case of about25-30 degrees thus causing the lateral movement of the slide clamprelative to the base. Because of the construction of the clamp apparatus20, the slide clamp 24 is able to rotate enough to interrupt thedetector beam 156 thus causing a false alarm. The slide clamp remains inthe occluding position even though the detector beam is interrupted. Asmentioned, false alarms can be a nuisance and slow down the process ofproviding medical care.

Although described above as a detector system that radiates a beamtransversely to the longitudinal axis of the base, other detectorsystems may be possible and may be accommodated by the configuration ofthe clamping apparatus 20.

Turning now to FIG. 21, in order to restrict excessive lateral rotationor movement of the slide clamp 24 along the direction of the arrow 104to avoid the situation shown in FIG. 20 above, a groove 106 is formed inthe bottom surface 36 of the slide clamp and a cooperatively shaped rib108 is formed on the rail 70 of the base 22, as described further below.Such cooperating structure will limit the amount of rotation of theslide clamp in relation to the base, even when an operator placesangular force on the pushing surface such as that shown in FIG. 20.

FIG. 22 shows a cutaway view of the automatic clamp apparatus 20 of FIG.21 wherein the cutting plane is parallel to the bottom surface 36 of theslide clamp 24. In this view, the portion of the rail 70 connecting therib 108 to the side edges 68 of the slide clamp is cutaway and notshown. The groove 106 and the rib extend parallel to the longitudinalcenter line 47 or the direction of the relative sliding movement betweenthe base 22 and the slide clamp. The groove extends from about the frontedge 46 of the slide clamp to the semi-circular rear edge 112 of theslide clamp. The groove also extends substantially perpendicular to thebottom surface of the slide clamp to a preselected depth. Thelongitudinal side walls 114, 116 of the groove are substantiallyparallel to each other near the front edge of the slide clamp. Thegroove becomes wider as it approaches the slide clamp rear edge 112 suchthat a flared portion 118 of the side wall 114 nearest the longitudinalcenter line 47 slopes toward the longitudinal center line, therebyforming a flared groove opening 120 at about the slide clamp rear edge.

The rib 108 extends from about the channel opening 122 at the front ofthe base 22 to about the semi-circular rear edge 124 of the base. Whenthe slide clamp 24 is first inserted into the channels 72 of the base,the flared portion 118 of the side wall 114 of the groove 106 guides therib into the flared groove opening 120 at the slide clamp rear edge 112.Preferably, the rib has a slightly smaller width than the width of thegroove near the front edge 46 of the slide clamp 24 so as to allow theslide clamp to slide feely between its open and occluding positionswithin the base. The rib is preferably slightly wider near the base rearedge 124 than at the channel opening 122 to facilitate injection moldingof the base. In one embodiment, the rib width near the base rear edge isabout 0.1 millimeter greater than at the channel opening. As such, sidewalls 126, 128 of the rib are at slight angles to the longitudinalcenter line 47.

It should be noted that the relative widths of the groove 106 and therib 108 are carefully selected so that contact between the groove sidewalls 114, 116 and the rib side walls 126, 128 substantially lessenslateral movement. As shown in FIG. 22, when a force is applied to theslide clamp 24 with a lateral force component along a directionindicated by the arrow 130, the left groove side wall 114 contacts afront portion 132 of the left rib side wall 126 while a rear portion 134of the right groove side wall 116 contacts the right rib side wall 128.Because of such contact, the applied lateral force results in andinsignificant amount of lateral movement of the slide clamp relative tothe base 22 along the direction of the arrow 130 so that the flow clampdetector apparatus of the pump will provide an accurate indication ofthe clamp configuration.

As illustrated in FIGS. 21 and 22, the groove 106 and the rib 108 arelocated to one side of the automatic clamp apparatus 20, in thisembodiment, to the right of the longitudinal center line 47. It will beappreciated that relative lateral movement between the slide clamp 24and the base 22 may also be minimized or eliminated by positioning thegroove and the rib on the opposite side of the longitudinal center line.In an alternative embodiment, there may be a groove and a rib on bothsides of the longitudinal center line to provide greater lateralstability. In yet other embodiments, the groove 30 may be located on thetop surface 34 of the slide clamp and the rib is formed at acorresponding location on the base.

While the particular automatic clamp apparatus as herein shown anddisclosed in detail is fully capable of obtaining the objects andproviding the advantages herein before stated, it is to be understoodthat it is merely illustrative of presently preferred embodiments of theinvention and that no limitations are intended to the details ofconstruction or design herein shown other than as recited in theappended claims.

1. A clamp apparatus for selectively preventing fluid flow through aresilient tube, comprising: a base having a tube aperture at which theresilient tube may be located, the base having a longitudinal centerline; a slide clamp slidably mountable on the base for linear movementbetween an occluding position and an open position, the slide clamphaving a longitudinal center line; a clamp aperture formed in the slideclamp for receiving the tube therethrough; a constricted region formedin the clamp aperture, the constricted region occluding the tube toprevent fluid flow through the tube when the slide clamp is in theoccluding position; an open region formed in the clamp aperture, theopen region allowing fluid flow through the tube when the slide clamp isin the open position; a flexible cantilevered locking arm mounted on thebase, the locking arm being biased toward a locking position to preventmovement of the slide clamp from the occluding position to the openposition, the locking arm being deflectable to allow subsequent movementof the slide clamp from the occluding position to the open position; alocking device formed in the slide clamp for engagement with the lockingarm when the slide clamp is in the occluding position to prevent theslide clamp from moving from the occluding position, the locking deviceadapted to receive the locking arm such that the locking arm isunstressed while engaged with the detent; a groove formed in one of theslide clamp and the base, the groove extending substantially parallel tothe longitudinal center line of the respective slide clamp or base inwhich it is formed; and a rib formed on one of the base and the slideclamp extending substantially parallel to the longitudinal center lineof the base or slide clamp on which it is formed, the rib sized andshaped to slide within the groove to restrict lateral movement of theslide clamp and base relative to each other.
 2. The clamp apparatus ofclaim 1 wherein the tube aperture of the base slidably receives theresilient tube such that the base may be slid along the tube to aselected position when the slide clamp is in the open position.
 3. Theclamp apparatus of claim 1 wherein the locking arm further comprises arelease tab for releasing the flexible arm from the slide clamp, toallow subsequent movement of the slide clamp from the occluding positionto the open position.
 4. The clamp apparatus of claim 3 wherein the basefurther comprises a stop surface located at a position adjacent therelease tab to interfere with movement of the release tab beyond apreselected range of movement.
 5. The clamp apparatus of claim 3 whereinthe release tab is located at a position offset from the longitudinalcenter line of the base.
 6. The clamp apparatus of claim 5 wherein therelease tab is disposed for deflecting the flexible arm out of thedetent to allow subsequent movement of the slide clamp from theoccluding position to the open position.
 7. The clamp apparatus of claim1 wherein the slide clamp further comprises a ramp to receive thelocking arm when the slide clamp is in the open position, the rampformed to be deeper than the arm whereby the arm is unstressed when theslide clamp is in the flow position.
 8. The clamp apparatus of claim 7wherein: the locking device comprises a detent formed in the slideclamp; the ramp is formed to guide the locking arm into the detentformed in the slide clamp as the slide clamp is being moved from theopen position to the occluding position to thereby lock the slide clampin the occluding position.
 9. The clamp apparatus of claim 1 wherein:the aperture is approximately tear-drop shaped; the constricted regioncomprises an elongated slot portion; the flow region comprises a roundedportion; the tube is located in the slot portion when the slide clamp isin the occluding position; and the tube is located in the round portionwhen the slide clamp is in the open position.
 10. The clamp apparatus ofclaim 1 wherein the tube aperture comprises a tube sleeve within which atube end may be permanently mounted.
 11. The clamp apparatus of claim 1wherein the tube aperture comprises a fluid passageway through the base,whereby the resilient tube is connected in fluid communication with thepassageway.
 12. The clamp apparatus of claim 1 further comprising apressure interface device located between the resilient tube and thebase, the pressure interface device having a pressure membrane mountedin a housing, the pressure membrane formed to conduct pressure increasesand decreases of the resilient tubing to a pressure sensor.
 13. Theclamp apparatus of claim 1 wherein the slide clamp further comprises afront pushing flange large enough to receive a digit of an operator usedto push the clamp apparatus into position in a medical infusion pump,the pushing surface being concave.
 14. The clamp apparatus of claim 13wherein the release tab is located at a position other than behind thepushing flange.
 15. The clamp apparatus of claim 14 the release tab islocated at a sideways position in relation to the pushing flange. 16.The clamp apparatus of claim 1 wherein: the locking arm furthercomprises a release tab for releasing the flexible arm from the slideclamp, to allow subsequent movement of the slide clamp from theoccluding position to the open position; the base further comprises astop surface located at a position adjacent the release tab to interferewith movement of the release tab beyond a preselected range of movement;the locking device comprises a detent formed in the slide clamp; theslide clamp comprises a ramp to receive the locking arm when the slideclamp is in the open position, the ramp formed to be deeper than thelocking arm whereby the locking arm is not under stress when the slideclamp is in the flow position, the ramp further formed to guide thelocking arm into the detent as the slide clamp is being moved from theopen position to the occluding position to thereby lock the slide clampin the occluding position; the slide clamp further comprises a frontpushing flange large enough to receive a digit of an operator used topush the clamp apparatus into position in a medical device, the pushingsurface being concave; and the release tab is located at a positionother than behind the pushing flange.
 17. The clamp apparatus of claim16 wherein the release tab is located at a sideways position in relationto the pushing flange.
 18. A clamp apparatus for selectively preventingfluid flow through a resilient tube, comprising: a base having a tubeaperture at which the resilient tube may be located, the base having alongitudinal center line; a slide clamp slidably mountable on the basefor linear movement between an occluding position and an open position,the slide clamp having a longitudinal center line; a clamp apertureformed in the slide clamp for receiving the tube therethrough; aconstricted region formed in the clamp aperture, the constricted regionoccluding the tube to prevent fluid flow through the tube when the slideclamp is in the occluding position; an open region formed in the clampaperture, the open region allowing fluid flow through the tube when theslide clamp is in the open position; a flexible cantilevered locking armmounted on the base, the locking arm being biased toward a lockingposition to prevent movement of the slide clamp from the occludingposition to the open position, the locking arm having a release tablocated at a position offset from a longitudinal center line of the basefor deflecting the locking arm from the locking position to allowmovement of the slide clamp to the open position; a detent in the slideclamp into which the locking arm is biased to the locking position andinto which the locking arm is located when the slide clamp is in theoccluding position to prevent the slide clamp from moving from theoccluding position, the detent being large enough to receive the lockingarm such that the locking arm is unstressed while in the detent; a stopsurface located on the base at a position adjacent the release tab tointerfere with movement of the release tab beyond a preselected range ofmovement; a ramp located on the base to receive the locking arm when theslide clamp is in the open position and to guide the locking arm into adetent formed in the slide clamp as the slide clamp is being moved fromthe open position to the occluding position to thereby lock the slideclamp in the occluding position, the ramp formed to be deeper than thearm whereby the locking arm is unstresssed when the slide clamp is inthe flow position; a groove formed in the slide clamp, the grooveextending substantially parallel to the longitudinal center line of theslide clamp; and a rib on the base extending substantially parallel tothe longitudinal center line of the base, the rib sized and shaped toslide within the groove of the slide clamp and to restrict lateral androtational movement of the slide clamp relative to the base.
 19. Theclamp apparatus of claim 18 wherein the slide clamp further comprises afront pushing flange large enough to receive a digit of an operator usedto push the clamp apparatus into position in a medical infusion pump,the pushing surface being concave.
 20. The clamp apparatus of claim 18wherein the tube aperture comprises a tube sleeve within which a tubeend may be permanently mounted.